With the development of display technology, a demand for display quality increases gradually. A flat panel display device with high image quality and high resolution becomes more and more popular, and attracts the attention of a manufacturer of display panel increasingly. Currently, the most common flat panel display devices include a plasma display panel (PDP), a liquid crystal display (LCD), and an organic light-emitting diode (OLED) display device.
Currently, a thin film transistor (TFT) is a main driving element in a liquid crystal display device and in an active matrix organic light-emitting diode (AMOLED) display device, and directly relates to a development direction of a flat panel display device with high performance. Thin film transistors have a plurality of structures, and there are a plurality of materials for manufacturing the corresponding structures, among the plurality of materials, low-temperature polysilicon is preferable. Since an arrangement of atoms of low-temperature polysilicon is regular, the carrier mobility thereof is high (10-300 cm2/Vs). For a voltage drive type liquid crystal display device, a polysilicon thin film transistor with a smaller area can achieve deflection driving of liquid crystal molecules because it has a high mobility, which reduces a volume occupied by the thin film transistor largely, increases a light transmission area, and results in a higher brightness and a higher resolution. For a current drive type active matrix organic light-emitting diode display device, a polysilicon thin film transistor can meet a requirement of driving current better. Further, by using a material of low-temperature polysilicon, a driving integrated circuit (IC) may be integrated onto an array substrate, or even be manufactured as a system on glass (SOG), causing the array substrate to have advantages such as a smaller weight, a smaller thickness, a lower power consumption.
Although a low-temperature polysilicon thin film transistor has the above advantages, to achieve a continuous driving capacity in an array substrate of low-temperature polysilicon thin film transistor, it is necessary to provide a storage capacitor (Cs) at the same time. Especially in a display panel with high resolution, it is generally necessary to provide a Cs with large capacity to a low-temperature polysilicon thin film transistor for meeting driving requirements. Currently, in a method for manufacturing a low-temperature polysilicon thin film transistor and a storage capacitor in an array substrate, two ion-implantation processes must be employed due to different ion-implantation regions. Specifically, using a photoresist mask formed of a photoresist, a lower electrode of a storage capacitor is formed by one ion-implantation process. Then, using a mask formed of a material which is used to form the metal layer of a gate, a source and a drain is formed by one ion-implantation process. Furthermore, an activation process is performed on dopant ions implanted by the ion-implantation processes generally by using a high-temperature furnace annealing method or a rapid thermal annealing method. However, it takes a long time (several hours) to perform a heating process and a cooling process when the high-temperature furnace annealing method is used, causing a long process time. It also needs an additional special rapid thermal annealing apparatus to employ the rapid thermal annealing method, causing the costs of equipment, maintenance, personnel, etc to increase.
It can be seen that, in the existing method for forming a low-temperature polysilicon thin film transistor and a storage capacitor in an array substrate, it is difficult to achieve mass production of array substrates of low-temperature polysilicon thin film transistor, due to not only its complex process and long process time but also the requirement of many expensive apparatuses and the increased production cost.